I. Field of the Invention
The present invention relates generally to exercise equipment including systems and devices for measuring the energy output of a person during specific exercise to aid in evaluating the physical condition of the individual. More specifically, the invention is directed to a stationary bicycle ergometer system which measures the energy expended by the operator of a pedal cranking system in which both additional rotational torque and resistance to rotational torque or braking force can be externally applied to the system by separate auxiliary devices. The system eliminates the need for a massive flywheel and the applied force on the pedal and crank assembly required to initially overcome the inertia of the flywheel and subsequently maintain its rotation. Instantaneous rotational speed of pedalling and angular position of the pedal and crank assembly are accurately measured by relatively simple and sensitive analog devices to provide accurate input for energy measurement and device control in order to minimize the isometric component of exercise.
II. Description of the Related Art
Bicycle ergometers have been widely used to impose defined levels of physical work on human subjects. This has been done both for purposes of research in exercise physiology and for diagnostic purposes with regard to exercise, stress testing, or the like. In one common type of such device, the work produced by the operator in manually maintaining rotation of a flywheel by driving the pedal and crank system of a stationary bicycle is measured against resistance produced by applying a known braking force to the flywheel.
Many of the patients that are tested on devices of the class described have chronic cardiac problems or are otherwise weak or infirm and, for this reason, one of the desirable goals of such devices is to reduce the minimum work input required to operate the bicycle ergometer prior to a deliberate application of a retarding force, i.e., the onset of a test. One prior solution to this problem involved the use of an auxiliary motor to overcome the inertia in the flywheel from rest to a selected speed of rotation and thereafter allowing the user to expend energy only in maintaining the operation of the bicycle ergometer against a specific known applied braking force or, in some cases, no applied force at all. An example of such a device is illustrated and described in U.S. Pat. No. 4,647,036 to A. Huszczuk, a co-inventor in the present application. That device does not, however, provide means to actually measure the work output generated.
In addition, the operation of such devices heretofore contrived by the very nature of the pedal crank involves the expending of a great deal of the user's energy by the way of an isometric component of exercise. This, of course, involves muscular contraction or changing muscle tension with the ends of the muscle staying relatively fixed in place. In other words, significant changes in tension may occur without appreciable compensating changes in muscle length. From the standpoint of the measurement of the user's or patient's physical condition or with respect to benefitting the patient's or user's health, isometric exercise is not as desirable as isotonic exercise. In isotonic exercise, the muscle tension or force exerted is kept relatively constant with respect to the length of the muscle. As force is increased, the muscle is allowed to stretch, for example. It would be a distinct advantage if such a device were to reduce the relative amount of isometric effort.
Thus, those working with devices of the bicycle ergometer type have long sought to reduce the lower limit on the work effort for a user so that the weakest and most infirm patients can be monitored and helped. It is an additional goal of the evolution of such machines to increase the relative amount of isotonic work associated with the use of the device relative to the amount of isometric, i.e., unproductive energy expenditure, so that the operation of the device is more beneficial to the user. In addition, simplification of such devices both mechanically and electrically would be beneficial.
Accordingly, it is a principal object of the present invention to provide a bicycle ergometer having the ability to reduce the relative amount of isometric muscular effort required to operate the device.
Another object of the present invention is to reduce the minimum energy required to effect operation of the bicycle ergometer.
A still further object of the present invention is to enable the direct measurement of work output produced by the user of such a device.
A still further object of the present invention is to devise a bicycle ergometer which has the ability to modulate braking torque on a real time basis in accordance with the sensed rotational torque, position and speed of the pedal and crank assembly in a closed loop feedback system to optimally perform work at any preset level regardless of the pedalling cadence.